New Measurement of $\mathit{B}\to {\mathit{D}}^{*}\mathit{\pi }$ Branching Fractions

The decays $\Upsilon \left(4S\right)\to B\overline{B}$, followed by $B\to D^{*}\pi$ and $D^{*}\to D\pi$, permit reconstruction of all kinematic quantities that describe the sequence without reconstruction of the $D$, with reasonably low backgrounds. Using an integrated $e^{+}{e}^{-}$ luminosity of $3.1{\mathrm{fb}}^{-1\mathrm{}}$ accumulated at the $\Upsilon \left(4S\right)$ by the CLEO-II detector, we report measurements of $B({\overline{B}}^0\to D^{*+}{\pi }^{-})=(2.81\pm 0.11\pm 0.21\pm 0.05)\times {10}^{-3\mathrm{}}$ and $B(B^{-}\to D^{*0}{\pi }^{-})=(4.34\pm 0.33\pm 0.34\pm 0.18)\times {10}^{-3\mathrm{}}$.